耐候冷镦钢在模拟海洋大气环境中的腐蚀行为

Corrosion behavior of weathering cold heading steel in simulated marine atmosphere

采用腐蚀失重法、宏观形貌观察、SEM、XRD、电化学测试对耐候冷镦钢在模拟海洋大气环境中的腐蚀行为进行了研究。结果表明,在模拟海洋大气腐蚀环境下,耐候钢表面锈层随腐蚀时间由浅黄色依次向棕黄色、红棕色转变;锈层截面形貌由薄而疏松且不连续演变为厚而致密且均匀分布;锈层微观形貌显示,表面锈层存在相对平滑、不规则圆形花状结构、闭环的环形巢结构、毛绒状结构等4个演变状态,但致密的毛绒状结构锈层对基体的保护能力明显提高;腐蚀产物主要由Fe_(3)O_(4)、γ-FeOOH、α-FeOOH组成,腐蚀初期主要是致密的Fe_(3)O_(4),腐蚀中期开始形成γ-FeOOH,腐蚀后期γ-FeOOH逐渐溶解并还原形成稳定的α-FeOOH,可对基体提供良好的保护作用;电化学分析显示:腐蚀24~72 h,耐候钢的阴极电流密度呈线性增大,且趋于稳定。耐候钢的腐蚀深度损失与腐蚀时间呈幂函数关系;受腐蚀过程不同腐蚀产物的影响,腐蚀速率呈现先增长后下降的变化规律。

The corrosion behavior of weathering cold heading steel was studied by corrosion weight loss method,macroscopic morphology observation,SEM,XRD and electrochemical test in simulated marine atmosphere.The results indicate that under the simulated marine atmospheric corrosion environment,the rust layer on the surface of weathering steel changes from light yellow to brownish yellow and reddish-brown with the corrosion time;the cross-sectional morphology of the rust layer changes from thin,loose and discontinuous to thick,dense and uniform distribution;the microscopic morphology of the rust layer shows that the surface rust layer has four evolution states:relatively smooth,irregular circular flower-like structure,closed-loop annular nest structure,and plush-like structure,However,the protection ability of the dense rust-like structure to the substrate is obviously improved;the corrosion products are mainly composed of Fe_(3)O_(4),γ-FeOOH,α-FeOOH,and the initial corrosion is mainly dense Fe_(3)O_(4),in the middle stage of corrosion,γ-FeOOH begins to form,in the later stage of corrosion,γ-FeOOH gradually dissolves and reduces to form stable α-FeOOH,which can provide good protection for the matrix;electrochemical analysis shows that the cathodic current density of weathering steel increases linearly and tends to be stable between 24 and 72 hours of corrosion.The corrosion depth loss of weathering steel has a power function relationship with the corrosion time.Affected by different corrosion products in the corrosion process,the corrosion rate shows a changing law of first increasing and then decreasing.